During periods such as start-up and shutdown, a steam turbine is exposed to changes in temperature that affect a temperature of the metal components of the steam turbine, such as the rotor. As a result of transitory thermal situations such as start-up, the rotor experiences thermal stress due to differences in metal temperature throughout the rotor as the steam turbine transitions from a non-operating state to an operating state and the rotor is heated. A start-up time of a steam turbine can affect the thermal stress experienced by the rotor.